Primary aerospace structures are assembled using high strength fasteners. In metallic structures these fasteners are assembled in interference fit holes (i.e. the fastener diameter is marginally larger than the hole diameter). However, due to the nature of composite materials it is currently inappropriate to use interference fit fasteners in composite laminate structures. Therefore, in composite material structures it is necessary to use clearance fit fasteners (i.e. the fastener diameter is smaller than the hole diameter). The extreme vibrations and high load cycles seen during an aircraft's life can cause clearance fit fasteners to spin or rotate in their hole. Although this does not necessarily affect the clamping force of the fastener, excessive rotation may have several other detrimental effects: fastener rotation may damage the surface of the structure under the fastener head and/or tail; and rotation can break the sealant applied around a fastener resulting in a potential fuel leak.